Study On The Thermal Characteristics Of The Mechanical Seal Seal

There is a new form of mechanical seal in the metal hydrometallurgical process pump which is called non-flowing mechanical seal. The cooling water do not cycle out of the seal chamber, so the cooling water is called non-flowing water.Although the non-flowing water do not cycle out of the seal chamber, it flows inside the seal chamber because of the rotating of the shaft. The water temperature will rise because the heat caused by the friction of the seal rings passes to it.The high water temperature prevents the crystallization of the liquid, but the temperature can not be too high. The key to correct use of this mechanical seal is reasonable control of the liquid temperature.The theoretical basis and the key technologies for using this mechanical seal is the fully understanding and grasping its heat transfer characteristics. In this paper, a theoretical study of the thermal characteristics under the steady and transient state for the non-flowing mechanical seal was carried out, the temperature distribution in seal rings and the temperature of sealing water in the seal chamber was obtained.The analytical expressions of temperature field and heat dissipating capacity for the composite fin which were composed by the two straight fins with unequally cross-section was obtained according to the principle of heat balance. The calculation results of the composite fin expressions are fully consistent with the classic formula in the condition that the cross section area of the two fin are equal.The analytical expressions of temperature field and heat dissipating capacity about the fin, which has a smaller cross-section area near the fin base and a larger one, were obtained respectively. The results showed that the larger the cross section area near the base, the better the heat transfer. The temperature of the fin with larger cross section area is lower than that with smaller cross section area when the amount of heat is fixed. The unequal cross-sectional straight fin model can be used to calculate the thermal characteristics of the bilateral heat transfer mechanical seal. For the double mechanical seal, the mechanical seal near the media is the bilateral heat transfer mechanical seal which one side of the seal contacts with the medium, and the other side contacts with water. The non-flowing mechanical seal is double mechanical seal which the non-flowing water do not flow out of the seal chamber.For the unilateral heat transfer mechanical seal, the fin model from Buck is used to calculate the temperature distribution of the mechanical seal in the steady state. The calculation result showed that the temperature of the seal ring gradually decreases with increasing distance to the seal faces. The impact of friction factor f, face pressure pc and shaft speed n to the face temperature was analyzed.Transient heat transfer characteristics of seal rings can be reflected by the relationship of temperature field and time. The method of separation of variables is used to calculate the temperature distribution of the mechanical seal in the transient state.The transient temperature distribution changes with time and at last it is consistent with the temperature distribution in the steady state. The influence of friction factor f, face pressure pc and shaft speed n to the face temperature of mechanical seal is analyzed.The sealing water temperature in the seal chamber is affected by many factors. The equation of heat balance for the system and the theory of dual-tank systems are used to obtain the temperature rise curves of seals and sealing water by seeing the seals and sealing water as a dual-tank system. The analysis of the influence factors was carried out.For the bilateral heat transfer mechanical seal, the face temperature distribution was calculated by using the unequal cross-section fin model.The influence of friction factor f, face pressure pc and shaft speed n to the face temperature of mechanical seal was analyzed. The results showed that the friction factor f, face pressure pc and shaft speed n all can increase the face temperature when they increase. The friction factor f, and face pressure pc have greater impact to the face temperature.